System for controlling a hydraulic pressing apparatus



April 24; 1962 KAZUO S'UGIMURA SYSTEM FOR CONTROLLING A HYDRAULICPRESSING APPARATUS Filed March 18, 1960 3 Sheets-Sheet 1 APril 24, 1952KAZUO SUGIMURA 3,030,775

SYSTEM FOR CONTROLLING A HYDRAULIC PRESSING APPARATUS Filed March 18.1960 3 Sheets-Sheet 2 J1EE).

3 Sheets-Sheet 3 KAZUO SUGIMURA SYSTEM FOR CONTROLLING A HYDRAULICPRESSING APPARATUS April 24, 1962 Filed March 18, 1960 United StatesPatent 3,030,775 SYSTEM FOR CONTROLLHIG A HYDRAULIC PRESSING APPARATUSKazuo Sugirnura, 1416 Mine, Sodeshi-cho, Ihara-gun, Japan Filed Mar. 18,1%0, Ser. No. 15,907 2 Claims. (Cl. 69-51) This invention relates to asystem for controlling a hydraulic pressing apparatus. The mostdesirable characteristics for hydraulic equipment, such as oil presses,are 1), large pressing capacity, (2), short operating time and (3),large output out of small input. There has long been a keen desire forsuch hydraulic equipment as presses and the like, to have these threecharacteristics at one time.

In this invention, this desire has been fulfilled by introducing intothe system of hydraulic apparatus, -a con ventional pump of any type, aset of pressure hydraulic accumulators, a hydraulic tank, a controlvalve, electromagnetic change-over valves, a hydraulically operatedcommunicating valve and two automatic pressure control switches, and byletting all these valves act correlatedly with each other by operatingan operating lever, to sup-- ply or exhaust, selectively, pressure ornon-pressure fluid into or out of a main cylinder and auxiliarycylinders of a hydraulic machine and thus making the main ram orauxiliary rams operate in multistage strokes.

One of the embodiments of this invention is illustrated in the drawings,and its operation and superior characteristics are explained in thefollowing descriptions.

In the drawings: FIG. 1 shows the apparatus of this invention applied toa hydraulic press; FIG. 2 shows communication between fluid pipes in acontrol valve; FIG. 3 show diagrammatically the electric circuitsconnecting the switches; FIG. 3-1 being a front view of the guide plantand control lever, FIG. 3-2 being a side elevational view of the guideplate and control lever, and 'FIG. 3-3 showing the electricalconnections; and FIG. 4 is a table showing the correlations between theelectrical connections and valve positions of the electro-magneticchange-over valves 33 and 36.

In FIG. 1, a main cylinder 1 and two auxiliary cylinders 2, beingrigidly connected with each other or being made of one block and alsobeing rigidly and properly fastened to their frame and bed plate 3constitute ,a hydraulic press.

A single acting ram 4 of the main cylinder 1 and two double acting rams5 of the two auxiliary cylinders 2 are all fastened to a press plate 6.A control valve 7 consists of a piston valve 8, having piston heads h,and I1 and a valve cylinder 9. This piston valve is connected by aconnecting rod 10 and pins 14 and 14 to an operating lever 12, whose oneend is joined by a pin 11 to a guide plate 13.

Each of oil pipes 15, 16, 17, 18 and 19 has an opening inside the wallof the control valve cylinder 9.

These openings are opened or shut by the piston heads h and h when thepiston valve 8 is shifted to the right or left, through the connectingrod .14 by the operating lever 12, which is pivoted about the pin 11 totake its position A, O, B, C or D, each designated on the guide plate13. Thus the pipes above mentioned are connected or disconnected witheach other. These connections are shown in FIG. 2, which will beexplained later.

An oil pump 21% sucks oil out of an oil tank 35 through an oil pipe 20,and delivers pressure oil through an oil pipe to the control valve 7,and then through an oil pipe 16 to a set of pressure oil accumulators 32which are connected to this pipe. Pressure oil is thus accumulated inthe accumulators, and then it is supplied to the main ice 2 cylinder 1and auxiliary cylinders 2, again through the oil pipe 16, control valve7 etc., or through a branch of the pipe 16 and an electro magneticchange-over valve 33 or 36, which may be either of a rotary type asshown in FIG. 1 or of a piston type, both of which areelectromagnetically operated as will be described later.

An electromagnetic clutch 30 couples the oil pump 28 with an electricmotor 29. An automatic normal pressure control switch 31 is connected tothe pressure oil accumulators 32, and opens or closes the electriccircuit of the clutch 30, as the oil pressure reaches its upper or lowerlimit of normal oil pressure. Thus the magnetic clutch 30 couples oruncouples the pump with the motor so as to keep normal oil pressureautomatically in the accumulators.

Similarly an automatic high pressure control switch 37, whose oilcircuit is directly connected to a delivery pipe 15 of oil pump 28, forthe electromagnetic clutch 30, closes or opens the electric circuit ofclutch 30 to keep the oil pressure of pump delivery at acertain higherpressure than the normal, and to supply this high pressure oil directlyto the main cylinder 1 from the pump, when communication of oil betweenthe main cylinder and accumulators is cut off.

Oil pipes 17 and 22 connect the control valve cylinder 9 and maincylinder 1.

An oil pipe 13 connects the control valve cylinder 9 and the lowerchambers of auxiliary cylinders 2.

A surge valve 34, provided between oil pipes 22 and 27 which connect anoil tank 35 and main cylinder 1, is so constructed that the valve opensto connect this tank and main cylinder so as to permit non pressure oilto flow freely between the two, when pressure oil is supplied tooperating means for the valve through an electromagnetic change-overvalve 33 and oil pipe 21, and that the valve 34 cuts off thecommunication of oil between the main cylinder and oil tank, whenpressure oil is released from the operating means for the valve and isexhausted to the oil tank through the oil pipe 21, changeover valve 33,pipes 24 and 26. This change-over valve 33, when its electric circuit isclosed, connects the operating means for the surge valve with pressureoil accumulators 32 through oil pipes 16 and 21, and when its electriccircuit is opened, the valve connects the operating means for the surgevalve with the oil tank 35 through oil pipes 2 24 and 26.

Another electromagnetic change-over valve 36, when its electric circuitis closed, connects the upper chambers of auxiliary cylinders 2 withpressure oil accumulators 32 through oil pipes 16 and 23 to supplypressure oil to the cylinders, and when the circuit is opened, the valveconnects the cylinders to the oil tank 35 through oil pipes 23, 25 and25 to exhaust oil from the cylinders.

The operating lever 12 and the guide plate 13 compose a control switchassembly as shown in the FIG. 3.

The guide plate 13 has a set of a pair of contact pieces 51,electrically connected with each other, three contact pieces 52, 53 and54; While the operating lever 12 has another set or contact pieces 51,52', 53' and 54'. Each of the contact pieces of the former set contactswith each other of those of the latter, so that the pieces 51, 52, 53and 54 mate respectively with the contact pieces 51', 52, 53' and 54-,and compose four switches, to close or open the circuits of theelectro-magnetic change-over valves 33 and 36, of the master switch forthe normal pressure switch 3:]. and of the master switch for the highpressure switch 37.

The pair of contact pieces 51, provided at the raising position A andthe lowering position B of the guide plate 13 and the contact piece 51on the control lever 12 compose a switch for the electric circuit of theelectromagnetic change-over valve '33; the contact piece 52 providedalong the lowering position B, the normal press position C and thestrong press position D of the guide plate and the contact piece 52'provided on the control lever 12 compose a switch for the electriccircuit of the electromagnetic change-over valve 36; the contact piece53 which is provided along the raised position A, the stop andpreparatory position 0, the lowering position B, and the normal pressposition C of the guide plate and the contact piece 53 provided on thecontrol lever 12 compose a switch for the electric circuit of the masterswitch of the normal pressure control switch 31 for the magnetic'clutch30 which couples the oil pump 28 with the electric motor 29.

The contact piece 54 provided at the strong position D of the guideplate and the contact piece 54 provided onthe control lever 12, composethe master switch of the high pressure control switch 37 also for themagnetic clutch 30.

The arrangement of control switch assembly and the electric connectionsbetween the switches, the change-over valves 33 and 36, the normalpressure control switch 31 and the high pressure control switch 37together with the magnetic clutch 30, are diagrammatically shown in theFIG. 3. In the FIG. 3, the FIG. 3-1 is the front view of the guide plate13 and the control lever 12, where the latter is shown by broken linestogether with contact pieces provided on it, the FIG. 3-2 is the sidesectional view of the above along the position of the lever 12, and theFIG. 3-3 is the electric connections as above mentioned.

FIG. 4 is a table showing the cor-relations between the electricconnections and valve positions of the electromagnetic change-overvalves 33 and 36, and the electric connections of master switches of thenormal pressure control switch 31 and of the high pressure controlswitch 37 for magnetic clutch 30, at each position of the operatinglever 12.

An embodiment of the present hydraulic apparatus as applied to an oilpress is explained below. This oil press is able to complete itspressing operation, consisting of five strokes, i.e., stop andpreparatory, raising, lowering, normal press and strong press strokes,and attains the desired characteristics as follows:

(1) Stop and Preparatory Stroke The operating lever 12 is set to theposition 0 then as shown in FIG. 2-1, in the control cylinder 9, theopening of the oil pipe 17 to the main cylinder 1 is shut by the pistonhead 11 of the piston valve 8.

The operating lever being at this position 0, the electric circuit ofthe electromagnetic change-over valve 33 is opened, and communicationbetween the main cylinder 1 and oil tank 35 through oil pipes 22 and 27is cut off by the surge valve 34. At this position, the electric circuitof another electromagnetic change-over valve 36 is also open, to cut oifthe upper chambers of auxiliary cylinders 2 from pressure oilaccumulators 32 and to connect the cylinders with oil tank 35.

Also, in the control valve cylinder, the opening of oil pipe 18 to thelower chambers of auxiliary cylinders is shut by the piston head h Thusthere is no oil flow into or out of the cylinders, and the rams do notmove but remain at their present position.

Also at this position 0, the openings of the oil pipe 15 from the oilpump, and of oil pipe 16 to the pressure oil accumulators 32 are bothopened and communicate with each other in the control valve cylinder 9between the two piston heads h and h Thus the pressure oil to beaccumulated is pumped into the pressure oil accumulators through thecontrol valve. With the operating lever, at its position 0, the masterswitch of automatic normal pressure control switch 31 closes. Thus 4 theoil in the accumulators is kept at its normal pressure, and now thepress is ready to work.

(2) Raising Stroke In order to apply a piece to be pressed to the press,the operating lever 12 is shifted from O to its raising position A. Thenthe control piston valve 8 takes the position as shown in FIG. 22, withthe opening of the oil pipe 17 to the main cylinder 1 still beingclosed, and the openings of pipes 15, 16 and 18 are opened tocommunicate with each other between the two piston heads h and h in thecontrol valve cylinder 9. Thus pressure oil is supplied from thepressure oil accumulators to the lower chambers of auxiliary cylinders 2to push rams 5 upwards, while the upper chambers are connected with theoil tank 35 through the pipe 23, the electromagnetic change-over valve36 whose electric circuit is open at this position A of the operatinglever, the pipes 25 and 26. Thus the oil in the upper chambers can beexhausted to the oil tank 35 as the auxiliary rams are raised bypressure oil which is supplied into the lower chambers as abovedescribed.

On the other hand, the switch a for the electromagnetic valve 33 beingclosed, this valve connects pipes 16 and 21 to supply pressure oil tothe operating means for surge valve 34, to connect main cylinder 1 withoil tank 35, and allow oil to escape freely from the cylinder to thetank as the main ram 4 is raised upwards.

Thus the press plate 6 is raised to a desired height, when the operatinglever is shifted back to its stop position 0, to keep the press plate 6at its desired height.

(3) Lowering Stroke The operating lever 12 is shifted from O to thelowering position B, then the control valve piston 8 takes the positionas shown in FIGS. 2-3. In this position, the difference in theconnection of the pipes in the control valve cylinder 9 between thisstroke and that of the raising stroke is that pipe 18 which connectswith the lower chambers of auxiliary cylinders 2 now communicates withthe port of exhaust pipe 19, whereas previously pipe 18 communicatedwith pressure oil pipes 15 and 16. Therefore, the oil in the lowerchambers of auxiliary cylinders 2 may freely escape to the oil tank 35through the pipe 18, the control valve cylinder and then the pipe 19.The upper chambers of the auxiliary cylinders 2 connect with pressureoil accumulators 32 through the pipes 23, the electromagneticchange-over valve 36, whose electric circuit is closed by the switch bat the position B of the operating lever 12, and pipe 16.

In this position, as the rams are lowered downward, non pressure oilflows freely into the main cylinder from the oil tank through the pipe27, surge valve 34 and pipe 22, since the surge valve is kept open asdescribed in the raising stroke.

Thus, as the auxiliary rams are lowered by pressure oil supplied to theupper chambers'of the auxiliary cylinders, oil in the lower chambers ofthe auxiliary cylinders is exhausted to the oil tank, and non pressureoil flows into the main cylinder as its ram is lowered.

It is clear, in this stroke, that the rams being lowered by pressure oilin the auxiliary cylinders, finish this stroke much quicker than whenthey are lowered by their own weight, as in the case of conventionalhydraulic presses. Moreover, this stroke is economical, because theamount of pressure oil, which is consumed only by auxiliary cylinders,is very small.

Thus, the rams are lowered until the press plate 6 touches the piecepressed. Then the operating lever 12 is shifted to its position C forthe next normal press stroke.

(4) Normal Press Stroke The operating lever 12 is shifted from B to thenormal press position C. Then the switch 0 and the master switch forautomatic normal pressure control switch 31 are closed, and the controlvalve piston 8 takes the position as shown in FIG. 24. In this case, thedifference in communication of pipes in the control valve cylinder fromthe lowering stroke, is that the port of pipe 17 is opened in thisstroke instead of being shut by the piston head k as in the loweringstroke and this pipe is connected with pipes 15 and 16.

At this position of the operating lever, the electric circuit of theelectromagnetic change-over valve 33 is opened to cut oh thecommunication between the main cylinder and oil tank by surge valve 34,and just as in the case in the lowering stroke, the electric circuit ofelectromagnetic change-over valve 36 is closed to communicate pressureoil to the upper chambers of auxiliary cylinders.

Thus, normal pressure oil controlled by automatic switch 3 1. issupplied to the main cylinder 1 from the pressure oil accumulators 32through the pipe 16, control valve 7, oil pipes 17 and 22, and to theupper chambers of auxiliary cylinders 2 as in the case of the loweringstroke to complete this stroke.

(5) Strong Press Stroke In the four strokes above described, oilpressure is controlled by the normal pressure control switch 31, andtherefore, the capacity of the press is normal.

Larger pressing capacity, when required, may be obtained by higher oilpressure, which is controlled by another automatic strong pressurecontrol switch 37.

In this stroke, the operating lever 12 is shifted from C to D. Then theswitch d closes the circuits of electromagnetic change-over valve 36 andthe master switch for automatic strong pressure control switch 37. Inthe control valve 7 the opening of pipe 16 is shut by the piston head hto cut oil? the communication between the oil pump and accumulators,while other pipe openings and their relative communications remain thesame as in the normal press stroke as shown in FIG. 2-5.

Thus, oil of higher pressure, controlled by the control switch 37 issupplied directly to the main cylinder 1 from the oil pump 28 throughthe pipe 15, control valve 7, pipes 17 and 22; and in addition to thisaccumulated oil is supplied from the accumulators 32 through the pipe16, change-over valve 36 and pipes 23, to the upper chambers ofauxiliary cylinders 2 giving strong overload pressing power to the pressplate 6.

When the normal or strong press stroke is thus completed, the operatinglever is to be shifted again to its position A for the raising stroke torepeat the same cycle.

In this hydraulic operating apparatus, as above described, a set ofpressure oil accumulators of ample capacity is supplied in the oilcircuit to enlarge the capacity of the pressure oil source, so that alarge amount of pressure oil can be supplied at one time to the presscylinders, with an oil pump of small capacity.

Therefore, by introducing an oil pump of small capacity and of any type,and by introducing a set of pressure oil accumulators into the oilsystem of a hydraulic press, and by the correlative actions of a controlvalve, two change-over valves, a surge valve and two automatic pressurecontrol switches, pressure oil of two different pressures from the twosystems of oil sources may be supplied to the main and/or auxiliarycylinders selectively, and

thus, a series of multistage strokes of speedy, eflicient and powerfulpressing operations may be obtained at low initial cost and low runningexpenses.

It is obvious that the application of this hydraulic apparatus is notlimited to a hydraulic press as above described, and that this may beapplied to other equipment such as moulding machine, machine tools etc.

I claim:

1. A hydraulic press comprising a main cylinder and at least oneauxiliary cylinder, a set of pressure oil accumulators, an oil pump, amotor, a magnetic clutch, said pump being driven by said motor throughsaid magnetic clutch to charge said accumulators with oil of normalpressure, an automatic normal pressure control switch for controllingsaid magnetic clutch to effect normal pres sure output, said pump alsoacting to charge said main cylinder directly with oil of high pressure,an automatic high pressure control switch for controlling said magneticclutch to effect high pressure output, an oil tank, a set of change-overapparatus consisting of a control valve, two electro-magneticchange-over valves, master switches for said change-over valves, a surgevalve and a control lever equipped with a connecting rod, said controllever acting to operate said control valve, and with electric contactsto close or open correlatedly with the control valve the switches forsaid electro-magnetic change-over valves, and the master switches forsaid automatic normal pressure control switch and said automatic highpressure control switch, to connect or disconnect selectively thecommunication of oil between said oil pump, said oil accumulators, saidoil tank and said main and auxiliary cylinders, whereby the rams of saidcylinders make a series of multistage strokes of speedy, efiicient andpowerful pressing powers.

2. A hydraulic press apparatus which consists of a raising means havinga control valve between an accumulator provided with an automatic normalpressure control switch and the lower side of an auxiliary cylinder, anoil pressure circuit having an electromagnetic change-over valve betweensaid accumulator and a surge valve, a lowering means having anelectromagnetic change-over valve between said accumulator and the upperside of the auxiliary cylinder, a normal press means having said controlvalve between said accumulator and a main cylinder, a strong press meanshaving said control valve between an oil pump provided with a strongpressure control switch and said main cylinder, and an operating meansadapted to selectively or coincidently operate a piston valve of saidcontrol valve, said two electromagnetic change-over valves, saidautomatic normal pressure control switch and said strong pressurecontrol switch respectively, by shifting an operating lever to therespective positions.

References Cited in the file of this patent UNITED STATES PATENTS1,086,738 Thompson et a1. Feb. 10, 1914 2,239,566 Mercier Apr. 22, 19412,324,697 Harrington et al July 20, 1943 2,337,848 Davis Dec. 28, 19432,790,305 Towler et al Apr. 30, 1957

